I have made an action animation with an IK rig. The mesh has a mirror, subsurf, and armature modifier.
I began making my character walk by using a keyboard sensor connected to an and brick connected to a motion and an action brick. I set the action to my walking animation and set the start to 0 and the end to 80 on play (I wanted to test it before I looped it) but when I pressed P and then W for my walking the character moved but the animation did not play.
Here is the .blend file